Sonny Bill Williams sat on the sidelines for Sydney Roosters training on Wednesday, but Boyd Cordner firmed as a likely starter for Sunday's grand final by taking part in the session.

Cordner and fellow forward Luke O'Donnell are fighting to prove their fitness for the season decider against Manly, and both participated in the light field session at Moore Park in an encouraging sign for the Roosters.

Mitchell Pearce also trained, having been quarantined from the rest of the team earlier this week after coming down with the flu.

Williams did not have his boots on and sat and watched as his team-mates warmed up with ball drills.

He was hampered by a calf injury in the lead-up to the finals series but has not missed a match, though he was suffering from food poisoning when he played last weekend's preliminary final win over Newcastle.

He was wearing a compression sock on Wednesday but would not appear to be in any doubt for what could be his last match of rugby league.

The Roosters are desperate for Williams to re-sign with the club, but the dual international is strongly weighing up a return to rugby union.

Neither Cordner nor O'Donnell was named in the Roosters' 17-man grand final team, but many believe both will be included.

Cordner has missed seven weeks with a broken ankle and has been racing the clock to be fit for the grand final.

Coach Trent Robinson has indicated he will rush the Dally M second rower of the year back for the clash if he is anything close to full fitness.

The 21-year-old has enjoyed a break-out season and played for New South Wales in State of Origin III in Sydney.

O'Donnell missed last week's preliminary final win over Newcastle with a hamstring injury, but running on Wednesday is a good sign for the veteran forward.

The former North Queensland hardman has grand final, State of Origin and Test experience, a valuable asset on the NRL's biggest stage.

Meanwhile, the Sea Eagles are refusing to rule out a stunning comeback by forward Joe Galuvao for the grand final.

Galuvao has missed most of the season with an Achilles tendon injury but is aiming to be included on the Sea Eagles' bench.